application_exercise/src/main.rs

mod global_state;
mod polygon;

///! This example illustrates how to resize windows, and how to respond to a window being resized.
use bevy::{
    input::{
        mouse::{MouseButtonInput, MouseWheel},
        ButtonState,
    },
    prelude::*,
    sprite::MaterialMesh2dBundle,
    window::WindowResized,
};

use bevy_egui::{egui, EguiContexts, EguiPlugin};
use global_state::GlobalState;
use polygon::ObjectInfos;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugin(EguiPlugin)
        .insert_resource(GlobalState::default())
        .insert_resource(ObjectInfos::default())
        .add_startup_systems((setup_camera, setup))
        .add_systems((
            print_mouse_events_system,
            update_ui_side_panel,
            on_resize_system,
        ))
        .run();
}

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
) {
    commands.spawn(MaterialMesh2dBundle {
        mesh: meshes.add(Mesh::from(shape::Quad::default())).into(),
        transform: Transform::default()
            .with_scale(Vec3::splat(4.))
            .with_translation(Vec3::new(100.0, 10.0, 0.0)),
        material: materials.add(ColorMaterial::from(Color::YELLOW)),
        ..default()
    });
}

// Spawns the camera that draws UI
fn setup_camera(mut cmd: Commands) {
    cmd.spawn(Camera2dBundle::default());
}

fn update_ui_side_panel(mut contexts: EguiContexts, mut global_state: ResMut<GlobalState>) {
    egui::Window::new("Hello").show(contexts.ctx_mut(), |ui| {
        if global_state.polygon_started {
            // TODO
        } else {
            if ui.button("New Polygon").clicked() {
                global_state.polygon_started = true;
            }
        }
    });
}

/// This system prints out all mouse events as they come in
fn print_mouse_events_system(
    mut mouse_button_input_events: EventReader<MouseButtonInput>,
    mut cursor_moved_events: EventReader<CursorMoved>,
    mut mouse_wheel_events: EventReader<MouseWheel>,
    mut global_state: ResMut<GlobalState>,
    mut object_infos: ResMut<ObjectInfos>,
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
) {
    for event in mouse_button_input_events.iter() {
        match event.button {
            MouseButton::Left => match event.state {
                ButtonState::Pressed => {
                    println!(
                        "Left mouse button pressed at {:?}",
                        global_state.cursor_position
                    );

                    let polygon = match object_infos.active_polygon() {
                        Some(polygon) => polygon,
                        None => object_infos.add_polygon(),
                    };

                    if polygon.add_point(global_state.cursor_position) {
                        global_state.polygon_started = false;

                        // TODO remove single points -> draw full polygon
                    } else {
                        commands.spawn(MaterialMesh2dBundle {
                            mesh: meshes.add(Mesh::from(shape::Quad::default())).into(),
                            transform: Transform::default()
                                .with_scale(Vec3::splat(4.0))
                                .with_translation(
                                    (global_state.cursor_position
                                        - (global_state.window_extent * 0.5))
                                        .extend(0.0),
                                ),
                            material: materials.add(ColorMaterial::from(Color::BLACK)),
                            ..default()
                        });
                    }
                }
                ButtonState::Released => (),
            },

            _ => (),
        }
    }

    // store latest mouse cursor location
    for event in cursor_moved_events.iter() {
        global_state.cursor_position = event.position;
    }

    for _event in mouse_wheel_events.iter() {
        //
    }
}

fn on_resize_system(
    mut resize_reader: EventReader<WindowResized>,
    mut global_state: ResMut<GlobalState>,
) {
    for e in resize_reader.iter() {
        // When resolution is being changed
        global_state.window_extent = Vec2::new(e.width, e.height);
    }
}